JPS62-085110A, published by the Japan Patent Office in 1987, discloses a blow-by gas processing device which collects blow-by gas blown out from cylinders to corresponding crank chambers of a V-shaped internal combustion engine in a gas introducing chamber which is disposed above the crank chambers and applies an oil separation process in an oil separator disposed above the gas introducing chamber. After separating an oil component in the oil separator, the blow-by gas is recirculated into an intake passage of the V-shaped internal combustion engine.
The gas-introducing chamber is formed in a space between a pair of cylinder banks of the V-shaped internal combustion engine. The V-shaped internal combustion engine comprises a plurality of crank chambers which are connected to the gas-introducing chamber via communicating holes.